What makes a stock move up or down?
The answer is in how much demandand supply there is for a stock at a given time. If there are more investors for a stock than is for sale at a given moment, then the available stock shares price rises to a higher level. If there are not enough stocks for sale available at the higher price, then the price of that stock goes up again. The same is true if the demand for a stock at a price decreases at a given moment. If there are fewer buyers than sellers than can agree on a given price, then the price of that stock goes down until the supply and demand of that stock stabilizes. If everyone that owned a stock wanted to sell that stock at market all at the same time, the value of that stock would plummet. If everyone wanted to buy more of the same stock at market price at the same time. The value and price of that stock would go up.
This article is written to the best of my knowledge. Please post a blog if you have any corrections to make.